The invention relates to a shaft rod, particularly for a heald shaft of a weaving machine, and includes the features of the preamble of claim 1. The invention further relates to a heald shaft provided with at least one of such a shaft rod.
Heald shafts of weaving machines are, as a rule, formed of a rectangular frame whose long sides are constituted by so-called shaft rods. Each shaft rod supports a shaft stave. Between the mutually parallel-arranged shaft staves healds are disposed which, by means of their end eyelets, are attached to the shaft staves. Each heald has at least one thread eyelet through which a warp thread extends which is moved by the motion of the heald shaft for shed forming. The healds are held on the shaft staves with a certain longitudinal play to enable them to freely align themselves in the lateral direction and to prevent them for being either compressed or extended. Such a play causes a continuous pounding or clattering of the healds against the shaft staves, creating a source of noise. Further, a stress on the healds is generated which may lead to heald breakage.
WO 01/48284 A1 discloses a heald shaft for a weaving machine. The shaft rods of the heald shaft each have a damping element on their sides facing the end eyelets of the healds. The damping element is arranged within the play range of the end eyelet, so that the latter may abut the damping element. Upon impact on the material having damping properties, lesser noise and mechanical stress on the heald are generated than in case of hard abutments.
The above principle is also realized according to U.S. Pat. No. 3,895,655 and Swiss Patent 588582.
Rubber or the like is being considered as the damping material. In the course of the threading step, the healds stand with their end eyelets on the lower damping element and remain suspended there by frictional engagement. Such a circumstance renders the thread-in of the healds more difficult. This is aggravated if a relatively small play is provided between the lower end eyelet and the damping element for the purpose of limiting the back-and-forth pounding of the healds in their longitudinal direction. If, on the other hand, a large play is provided for the operation, the damping effect remains limited.
It is therefore an object of the invention to provide a shaft rod which ensures a low-noise operation. It is further an object of the invention to provide a method of outfitting a heald shaft which includes at least one shaft rod as described above and where the thread-in of the healds may be effected in a manner as uncomplicated as possible.